Feedback control in an FDD TDD-CDMA system

ABSTRACT

Active control feedback between a base station and user equipment in a wireless communications network is achieved by allocating a first time slot within a frame for a UE to transmit a beacon signal to the base station, where the beacon signal is separate from data signals in the frame, allocating a second time slot within the frame for the base station to transmit a control signal in response to the beacon signal, and allocating other timeslots for the base station to operate in full duplex FDD mode. The control signal provides a basis upon which the UE adjusts a transmission parameter, such as power.

BACKGROUND OF THE INVENTION

Time division-code division multiple access (TD-CDMA) is an airinterface technology that combines the benefits of the three elementalconcepts in a universal mobile telecommunication system (UMTS): timedivision multiple access (TDMA); code division multiple access (CDMA);and time division duplex (TDD). TDD, in particular, uses the same radiochannel for both uplink and downlink communications, and discriminatesbetween signals by separating the transmissions in time. One of thebenefits obtained by operating both links on the same frequency is theability to exploit channel reciprocity.

Channel reciprocity gives equipment the ability to derive informationabout uplink channel conditions from downlink channel conditions basedupon signals received by the user equipment (UE). Pathloss is oneexample of channel information that can be obtained from channelreciprocity. Knowledge of the uplink pathloss enables open-loop powercontrol to be employed for uplink transmissions. For example, uplinkpower control is important for the operation of the CDMA element ofTD-CDMA as it counteracts the near-far effect that would otherwise beencountered if all UEs transmitted at a fixed power regardless of theuplink pathloss.

The open-loop uplink power control feature provides a significantadvantage when coupled with a multiple access data transmission systemthat is used for packet-based communication and/or shared channels. Whenaccess to a limited number of uplink channels is shared between a largepopulation of terminals it is imperative that access to the channels canbe switched between terminals with minimal latency. A data terminal thatcan derive information needed to access uplink channels from thedownlink transmissions (beacon signals) has a significant advantage overa terminal that relies on the (lengthy) configuration of a dedicatedchannel in order to establish a feedback channel.

However, channel reciprocity cannot always be guaranteed. For exampleTDD transmissions may not be permitted in certain frequency spectrumallocations; this is a regulatory issue and may be used to protect otherwireless equipment in the same or adjacent frequency bands. In thesesituations the correlation between uplink and downlink channels is lostbecause the channels are transported on carrier frequencies that areseparated in frequency by an amount that is greater than the coherencebandwidth of the channel (usually, only a few MHz separation issufficient to cause the uplink and downlink fading profiles to beindependent).

In high speed mobile applications, the time delay between downlink anduplink transmissions may exceed the coherence time of the channel. Themaximum time delay that can be tolerated is a function of the mobilespeed and the RF carrier frequency used, with the coherence timereducing with increasing speed and RF carrier frequency. Also, the useof multiple transmit and/or receive antennas at the network and/or themobile terminal can introduce unintentional decorrelation between theuplink and downlink channels.

If the TD-CDMA air interface is to be used in applications where thecorrelation between the uplink and downlink path loss is not guaranteed,then it would be advantageous to find a substitute for channelreciprocity.

BRIEF SUMMARY OF THE INVENTION

Although it is desirable to support air interfaces where the pathloss isnot reciprocal, known conventional methods do not deal directly with theevolution or adaptation of an air interface that uses channelreciprocity to deliver key features and advantages where channelreciprocity is not guaranteed. The adaptation provided in embodiments ofthe invention introduces a new technique for uplink channel control thatuses a feedback scheme as a substitute for the absence of channelreciprocity, with minimal impact on the ability of the air interface tosupport uplink shared channels.

Embodiments of the present invention enable active feedback controlbetween a base station and user equipment (UE). In particular, theoperation of a system designed for TDD, or unpaired operation, isexpanded to operate in FDD, or paired, mode. For example, an uplinkbeacon function (for power control) and a modified random access processsubstitute for the information lost due to the lack of channelreciprocity in paired operation. Embodiments of the invention allow aterminal to transmit the uplink physical channel control signal(UL_Beacon) independently from the uplink physical channel. Therefore,the implementation of closed loop feedback may operate in the absence ofan uplink physical channel. In one embodiment, a UE allocates a timeslot for a beacon signal separated from the time slots for data in aframe. A second time slot is allocated within the frame for the basestation to transmit a control signal in response to the beacon signal.The control signal instructs the UE to adjust a transmission parameter.

A UL_Beacon signal may be combined with a physical layer common controlchannel (PLCCH) to form a feedback system. A dedicated timeslot groupsall of the UL_Beacon signals from multiple UEs in a specific uplinktimeslot. By grouping the UL_Beacon signals together, embodiments obtainseparation between the UL_Beacon signals and the standard uplinkphysical channels. Additionally, in a synchronous system embodiments ofthe invention detect and cancel the UL_Beacon signals from other cellsites (inter-cell interference). The PLCCH carries feedback informationto the UEs that are transmitting UL_Beacon signals. The PLCCH can sharea timeslot with other physical channels by exploiting the CDMA aspect ofthe system.

In other embodiments, the number of supported UEs can be increased byfractionating the use of the UL_Beacon and PLCCH across a multiframeperiod. Fractionation may also prevent timeslot blocking where halfduplex UEs have a long UL/DL switching time. Additionally, support forhalf duplex terminals is implicit due to the nature of the TDMA framestructure. The system may manage the allocation of resource across thepopulation of terminals such that the full capacity of the base stationcan be utilized even when only half-duplex terminals are deployed. Inembodiments of the invention, full-duplex terminals can be still besupported along with half duplex UEs.

Moreover, in other embodiments, a radio resource control (RRC) connectedstate covers the subset of terminals that are in cell forward accesschannel (Cell_FACH), which are also transmitting UL_Beacon and receivingPLCCH, thus creating an active control feedback channel. Management ofthe UEs that are in Cell_Active state may remove users that are lessactive, and may add users that are newly active while retaining usersthat may have on-going data transfer requirements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cellular communication system according toembodiments of the invention;

FIG. 2 illustrates a timeslot arrangement for uplink and downlinkmessages supporting the UL_Beacon and its corresponding PLCCH within aTD-CDMA frame structure modified to support FDD according to embodimentsof the invention;

FIG. 3 illustrates fractionation in different frames at the base stationaccording to embodiments of the invention;

FIG. 4 illustrates UTRA RRC connected modes according to embodiments ofthe invention;

FIG. 5 illustrates a computer system that may be employed to implementembodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an example of a cellular communication systemaccording to embodiments of the invention. The network includes a userequipment (UE) domain, a radio access network (RAN) domain, and a corenetwork domain. The UE domain includes user equipment 110 thatcommunicate with at least one base station 112 in the RAN domain via awireless interface. The RAN domain may also include a network controller(RNC) 118 (e.g., radio network controller), such as that used in UMTSsystems. Alternatively, such functionality may be distributed betweenthe Node Bs and an access gateway (AGW)(not shown) or other controllerin the core network. FIG. 1 also illustrates an optional radio resourcemanager (RRM) 114. The RRM may perform functions otherwise performed bythe Node Bs or an AGW in some embodiments.

The core network (CN) 116 includes, in this example, a serving GPRSsupport node (SGSN) 120, and a gateway GPRS support node (GGSN) 122. Thecore network is coupled to an external network 124. The SGSN 120 isresponsible for session control, including keeping track of the locationof the UEs. The GGSN 122 concentrates and tunnels user data within thecore network 116 to the ultimate destination (e.g., an Internet serviceprovider) in the external network 124. Further details may be found inthe 3GPP UMTS technical specifications, such as TS23.246 v6.4.0 “3rdGeneration Partnership Project; Technical Specification Group Servicesand System Aspects; Multimedia Broadcast/Multicast Service (MBMS);Architecture and Functional Description (Release 6),” published by the3GPP Support Office, 650 Route des Lucioles—Sophia Antipolis,Valbonne—FRANCE, which are incorporated by reference herein.

Further details regarding exemplary communications systems that mayimplement embodiments of the invention may be found in 3GPP UMTStechnical specifications, such as TR 23.882, “3GPP System ArchitectureEvolution: Report on Technical Options and Conclusions”; TR 25.912,“Feasibility Study for Evolved UTRA and UTRAN”; TS 23.101, “GeneralUniversal Mobile Telecommunications System (UMTS) Architecture,” all ofwhich are incorporated by reference herein.

TDD to FDD Evolution

A system designed for operation in Time Division Duplex (TDD) mode hasbase stations and terminals that transmit and receive at orthogonalpoints in time. In normal operation terminals are in receive mode whenthe base station is transmitting, and base stations are in receive modewhen terminals are transmitting. In conventional TDD implementations,neither base stations nor the terminals are able to transmit and receiveat the same points in time because the same frequency is used for uplinkand downlink communication.

Such a system can be adjusted to operate in Frequency Division Duplex(FDD) mode, where the uplink and downlink communications occur ondifferent frequencies. According to embodiments of the invention, tomake full and efficient use of the frequency spectrum resources, thebase stations are adapted to transmit and receive at the same time. Thisis possible since the uplink and downlink communications now occur ondifferent frequencies. The terminals, however, retain the restriction oftransmitting and receiving at orthogonal points in time to retain thesimplicity of not having to transmit and receive at the same time (e.g.,no duplexer required). The full use of the frequency spectrum is thenobtained by allocating the resource across a plurality of terminals.

Additional measures may be needed if there are aspects of the airinterface that rely on the channel reciprocity that can be assumed forTDD systems. In the case of TD-CDMA, modifications may be made for thecorrect operation of uplink power control and rate adaptation. This canbe achieved by defining an uplink physical control channel used forestimating the uplink channel conditions and a downlink channel used tofeed back control information to the terminal. These channels may notneed an associated data physical channel to be operational.

Modifications may be made to the random access channel. This may beachieved by introducing an additional indicator step at the start of anyphysical random access. A new uplink physical channel carries the randomaccess indicators. A new downlink physical channel carries the responseto received uplink indicators.

Uplink Physical Channel Control Signal

When pathloss reciprocity is not available, the combination of an uplinkphysical channel control signal with a downlink feedback channel may beused to keep the terminal informed of the condition of the uplinkchannel. The uplink physical control signal is referred to herein as an“Uplink Beacon” (UL_Beacon).

In general, a system that supports shared channels may also supportshared access to a large number of terminals. To extract the maximumbenefit from the resulting trunking gain, shared channels can be quicklyand efficiently re-allocated between the population of UEs. To obtainrapid access to the uplink shared channels, terminals can transmit atthe correct power with their first transmission so that latency can bekept to a minimum.

According to embodiments of the invention, the RNC or other controller(e.g., other controller having its functionality in the core network)allocates resources so that the physical channel control signal isseparate from the uplink (shared) physical channel. Thus, terminals areable to transmit an UL_Beacon independently of their access to theuplink shared channel. The system may implement a closed loop controlsystem, in which the base station detects the received power and/orother channel information from the UL_Beacon, and sends controllingcommands back to each terminal to keep the terminal informed of thechannel conditions observed at the base station.

In certain embodiments, the closed loop control system is simply basedon the UL_Beacon power received at the base station. The base stationmay send power control commands on a shared downlink channel to eachterminal based on the power received from the UL_Beacon signal. Eachpower control command may, for example, indicate whether terminal powershould be increased or decreased by a predetermined amount. Thisdownlink channel is referred to as the “Physical Layer Control Channel”(PLCCH). The capacity of the PLCCH may be matched to the number of bitsrequired in the feedback field and the number of UL_Beacon signals thatcan be simultaneously supported. That is, each UL_Beacon may correspondto one bit of the PLLCH. All terminals transmitting UL_Beacon signalsmay receive this channel and extract the relevant feedback field.

It is possible to extend the complexity of the control loop by sendingcontrol commands based on other aspects of the UL_Beacon signal asreceived by the base station, such as time-of-arrival, and channelimpulse response. The amount of resource that is required for thefeedback channel increases with the size (in bits) of the feedbackinformation to each UE.

For example, for air interface technologies with a TDMA element, it ispossible to adapt the TDMA frame structure to provide separation betweenthe UL_Beacon and the normal physical channels by dedicating at leastone uplink time slot per frame (or at least one time slot permulti-frame) to carrying UL_Beacon signals.

By placing UL_Beacon signals in a dedicated timeslot, adedicated-detection scheme can be applied which may include performanceenhancing features such as intra-cell cancelling (for alleviating theeffects of cross-correlation interference between UL_Beacon signalstransmitted by multiple terminals in the same cell), or inter-cellcancelling (for reducing the interference from neighboring cells in thecase where the UL_Beacon timeslots are time synchronized).Cross-interference between UL_Beacon and normal uplink bursts is avoidedby the separation obtained from the use of separate time slots.

Those skilled in the art will recognize that there are a large number ofpossibilities for the arrangement of a UL_Beacon and its associatedPLCCH within the frame structure according to embodiments of theinvention. More than one UL_Beacon and PLCCH per frame could besupported if the feedback update rate is required to be faster than theframe rate (at the expense of system capacity). For system applicationsthat can tolerate a slower feedback rate, embodiments may fractionatethe use of the UL_Beacon timeslot (and the associated PLCCH).

When fractionation is employed, the RNC or other controller may allocatethe UL_Beacon timeslot in a given frame to a group of terminalsdepending on the current fractionation phase, thus increasing the numberof terminals that can be supported with active physical channel feedbackcontrol. The maximum fractionation cycle length may be determined by thefeedback update rate that the system requires in order to meet itsperformance targets.

FIG. 2 illustrates an example of a timeslot arrangement supporting theUL_Beacon and its corresponding PLCCH within a TD-CDMA frame structuremodified to support FDD. In this example, the PLCCH 212 shares atimeslot with another downlink shared channel. This is possible sincenormal downlink physical channels are used to transmit the PLCCH. Thedownlink frame also comprises a downlink beacon timeslot 206, an accesscontrol timeslot 208, and normal traffic carrying timeslots 210. Theuplink frame comprises a UL_Beacon control timeslot 216, an accesscontrol timeslot 218, and normal traffic carrying timeslots 214.

FIG. 3 illustrates an example where fractionation is employed. TheUL_Beacon and PLCCH timeslots are active in every frame at the basestation 302. However, terminal 304, terminal 306, and terminal 308 havebeen assigned a different fractionation phase. FIG. 3 illustrates thecase where the fractionation phase is 3. For example, the fractionationphase of terminal 304 occurs in frame #0 310, the fractionation phase ofterminal 306 occurs in frame #1 312, and the fractionation phase ofterminal 308 occurs in frame #2. Since the fractionation phase is 3, thephase for terminal 304 occurs again in frame #3 316.

Half Duplex Terminals

Embodiments of the invention enable terminals to operate in half duplexor full duplex mode. In a half duplex system, base stations andterminals do not transmit and receive simultaneously. When such a systemis evolved to operate in paired spectrum, it becomes inefficient if basestations retain their half duplex operation. It is not necessarilyinefficient for the terminals to do so, however, since half duplexoperation may have some advantages in the design and implementation ofthe terminal.

Nonetheless, there are some points that should be considered. Forexample, a single terminal may not be able to access all transmit andall receive slots. Therefore, the system may have to manage resourcesacross the population of terminals to ensure all the available resourcesat the base station are efficiently utilized. To prevent blocking oftimeslots, half duplex terminals may be operated with a fractionationcycle of greater than one. In particular, this may also apply for thecase where there are more than one UL_Beacon timeslot per, frame. Thereis a time delay for half duplex terminals to switch between transmit andreceive functions. In some cases this delay exceeds the guard periodinserted between consecutive timeslots. In the half duplex terminalcase, the terminal is unable to transmit and receive on adjacenttimeslots. This will affect the locations of the UL_Beacon, PLCCH, andother common channels. Accordingly, the timeslot arrangement may beadjusted when the system is configured.

Terminal Management

Embodiments of this invention separate uplink control from the uplinkphysical traffic. This allows the control feedback to operate even whenthe terminal does not have data to send, with the consequence thatuplink shared channels can be used with maximum efficiency.

To use shared channels efficiently, a relatively large user base may beneeded. At the same time, the network resources required to support thecontrol feedback channels for these terminals need to be minimized. Ingeneral, the number of users that can be supported with active controlfeedback channels is smaller than the typical number of users per cell.Therefore, the terminals in this active state may be managed.

In UMTS terminology, embodiments of the invention provide a newUniversal Terrestrial Radio Access- Radio Resource Control-Connected(UTRA RRC-Control) sub-state into the system. UTRA systems alreadysupport the idea of different RRC-Connected states (see, TS25.331 RadioResource Control (RRC) Protocol Specification, which is incorporatedherein by reference), e.g., CELL_DCH, CELL_FACH etc. This sub-state isreferred to as the CELL_ACTIVE state. FIG. 4 illustrates this sub-statein context with other UTRA RRC-connected states. A UE in a Cell_Activesub-state transmits the physical channel control part of the uplinkphysical channel only, and nothing else (i.e., no data).

As shown in FIG. 4, CELL_ACTIVE sub-state is a sub-state of CELL_FACHstate 404. In general, UEs in CELL_FACH state have an RRC connection,but they may not be actively transferring data. Out of the population ofUEs in CELL_FACH state 404, a smaller number of UEs, determined by thenetwork to be the most-active UEs, are supported in a CELL_ACTIVE state406. In this state, the UEs transmit the physical channel control signaland listen to the associated feedback channel from the network. Becausethe UE is aware of the uplink pathloss conditions from the feedbackchannel, it can have instant access to the uplink shared channels, andthe resource allocator (controller) in the network can treat the UEaccordingly.

The rules governing which UEs are maintained in CELL_ACTIVE state aredecided by the network (e.g., through the RNC) and may be based onfactors such as the volume of data transfer required by the UE, the datatransfer rate required by a UE, the frequency of short bursts of datatransfer, the total number of UEs in CELL_FACH state, the time since thelast data transfer, the UE power saving requirements, etc.

Note that UEs in CELL_ACTIVE state have their transmitters active,therefore it is necessary for these UEs to monitor the status of thedownlink and automatically come out of CELL_ACTIVE state if the downlinkis deemed to be out-of-synchronization (for example, very high downlinkerrors or low received signal strength). This feature prevents UEscontinuing to transmit in a state where the feedback channel may beunreliable and thus causing interference.

While the invention has been described in terms of particularembodiments and illustrative figures, those of ordinary skill in the artwill recognize that the invention is not limited to the embodiments orfigures described. Although embodiments of the present invention aredescribed, in some instances, using UMTS terminology, those skilled inthe art will recognize that such terms are also used in a generic senseherein, and that the present invention is not limited to such systems.

Those skilled in the art will recognize that the operations of thevarious embodiments may be implemented using hardware, software,firmware, or combinations thereof, as appropriate. For example, someprocesses can be carried out using processors or other digital circuitryunder the control of software, firmware, or hard-wired logic. (The term“logic” herein refers to fixed hardware, programmable logic and/or anappropriate combination thereof, as would be recognized by one skilledin the art to carry out the recited functions.) Software and firmwarecan be stored on computer-readable media. Some other processes can beimplemented using analog circuitry, as is well known to one of ordinaryskill in the art. Additionally, memory or other storage, as well ascommunication components, may be employed in embodiments of theinvention.

FIG. 5 illustrates a typical computing system 500 that may be employedto implement processing functionality in embodiments of the invention.Computing systems of this type may be used in the the radio controllers,the base stations, and the UEs, for example. Those skilled in therelevant art will also recognize how to implement the invention usingother computer systems or architectures. Computing system 500 mayrepresent, for example, a desktop, laptop or notebook computer,hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe,server, client, or any other type of special or general purposecomputing device as may be desirable or appropriate for a givenapplication or environment. Computing system 500 can include one or moreprocessors, such as a processor 504. Processor 504 can be implementedusing a general or special purpose processing engine such as, forexample, a microprocessor, microcontroller or other control logic. Inthis example, processor 504 is connected to a bus 502 or othercommunications medium.

Computing system 500 can also include a main memory 508, such as randomaccess memory (RAM) or other dynamic memory, for storing information andinstructions to be executed by processor 504. Main memory 508 also maybe used for storing temporary variables or other intermediateinformation during execution of instructions to be executed by processor504. Computing system 500 may likewise include a read only memory(“ROM”) or other static storage device coupled to bus 502 for storingstatic information and instructions for processor 504.

The computing system 500 may also include information storage system510, which may include, for example, a media drive 512 and a removablestorage interface 520. The media drive 512 may include a drive or othermechanism to support fixed or removable storage media, such as a harddisk drive, a floppy disk drive, a magnetic tape drive, an optical diskdrive, a CD or DVD drive (R or RW), or other removable or fixed mediadrive. Storage media 518, may include, for example, a hard disk, floppydisk, magnetic tape, optical disk, CD or DVD, or other fixed orremovable medium that is read by and written to by media drive 514. Asthese examples illustrate, the storage media 518 may include acomputer-readable storage medium having stored therein particularcomputer software or data.

In alternative embodiments, information storage system 510 may includeother similar components for allowing computer programs or otherinstructions or data to be loaded into computing system 500. Suchcomponents may include, for example, a removable storage unit 522 and aninterface 520, such as a program cartridge and cartridge interface, aremovable memory (for example, a flash memory or other removable memorymodule) and memory slot, and other removable storage units 522 andinterfaces 520 that allow software and data to be transferred from theremovable storage unit 518 to computing system 500.

Computing system 500 can also include a communications interface 524.Communications interface 524 can be used to allow software and data tobe transferred between computing system 500 and external devices.Examples of communications interface 524 can include a modem, a networkinterface (such as an Ethernet or other NIC card), a communications port(such as for example, a USB port), a PCMCIA slot and card, etc. Softwareand data transferred via communications interface 524 are in the form ofsignals which can be electronic, electromagnetic, optical or othersignals capable of being received by communications interface 524. Thesesignals are provided to communications interface 524 via a channel 528.This channel 528 may carry signals and may be implemented using awireless medium, wire or cable, fiber optics, or other communicationsmedium. Some examples of a channel include a phone line, a cellularphone link, an RF link, a network interface, a local or wide areanetwork, and other communications channels.

In this document, the terms “computer program product,”“computer-readable medium” and the like may be used generally to referto media such as, for example, memory 508, storage device 518, orstorage unit 522. These and other forms of computer-readable media maystore one or more instructions for use by processor 504, to cause theprocessor to perform specified operations. Such instructions, generallyreferred to as “computer program code” (which may be grouped in the formof computer programs or other groupings), when executed, enable thecomputing system 500 to perform functions of embodiments of the presentinvention. Note that the code may directly cause the processor toperform specified operations, be compiled to do so, and/or be combinedwith other software, hardware, and/or firmware elements (e.g., librariesfor performing standard functions) to do so.

In an embodiment where the elements are implemented using software, thesoftware may be stored in a computer-readable medium and loaded intocomputing system 500 using, for example, removable storage drive 514,drive 512 or communications interface 524. The control logic (in thisexample, software instructions or computer program code), when executedby the processor 504, causes the processor 504 to perform the functionsof the invention as described herein.

It will be appreciated that, for clarity purposes, the above descriptionhas described embodiments of the invention with reference to differentfunctional units and processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, processors or domains may be used without detracting from theinvention. For example, functionality illustrated to be performed byseparate processors or controllers may be performed by the sameprocessor or controller. Hence, references to specific functional unitsare only to be seen as references to suitable means for providing thedescribed functionality, rather than indicative of a strict logical orphysical structure or organization.

Although the present invention has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Rather, the scope of the present invention is limitedonly by the claims. Additionally, although a feature may appear to bedescribed in connection with particular embodiments, one skilled in theart would recognize that various features of the described embodimentsmay be combined in accordance with the invention.

Furthermore, although individually listed, a plurality of means,elements or method steps may be implemented by, for example, a singleunit or processor. Additionally, although individual features may beincluded in different claims, these may possibly be advantageouslycombined, and the inclusion in different claims does not imply that acombination of features is not feasible and/or advantageous. Also, theinclusion of a feature in one category of claims does not imply alimitation to this category, but rather the feature may be equallyapplicable to other claim categories, as appropriate.

1. A method for enabling active control feedback between a base stationand user equipment (UE) in a wireless communications network, the methodcomprising: allocating, by a controller, a first time slot within aframe for a UE to transmit a beacon signal to the base station, whereinthe beacon signal is separate from data signals in the frame, andincludes uplink physical channel information; allocating, by thecontroller, a second time slot within the frame that is different to thefirst time slot for the base station to transmit a control signal inresponse to the beacon signal, the control signal for providing a basisupon which the UE adjusts a transmission parameter, wherein allocatingthe second time slot to the control signal comprises allocating thesecond time slot to the control signal using a first code of a codedomain and allowing another downlink signal that is not the controlsignal to use a second code of the code domain to share the second timeslot with the control signal, wherein the first code differs from thesecond code; and allocating, by the controller, other timeslots for thebase station to operate in full duplex frequency division duplex (FDD)mode.
 2. The method of claim 1, wherein data signals are not allocatedto the first time slot.
 3. The method of claim 1, wherein the first andsecond time slots operate in full duplex FDD mode.
 4. The method ofclaim 1, wherein the transmission parameter comprises power.
 5. Themethod of claim 1, wherein the control signal is based upon at least onefactor from a group consisting of: path loss computed based upon thereceived power of the beacon signal; time of arrival of the beaconsignal; and channel impulse response in response to the beacon signal.6. The method of claim 1, wherein allocating a first time slot within aframe for the UE comprises allocating the first time slot within atleast some successive frames to different UEs for transmission ofrespective different beacon signals, and allocating a second time slotwithin a frame for the base station comprises allocating the second timeslot to the base station for transmission of different control signalswithin the at least some successive frames to the different UEs.
 7. Themethod of claim 1, further comprising; determining, by the controller,to which UE the first time slot should be allocated based upon at leastone factor from a group consisting of: expected volume of data transferexpected; required data transfer rate; frequency of short bursts of datatransfer; total number of UEs connected to the network; time since lastdata transfer; and UE power saving requirements.
 8. A controller forenabling active control feedback between a base station and UE in awireless communications network, the controller comprising logic for:allocating a first time slot within a frame for a UE to transmit abeacon signal to the base station, wherein the beacon signal is separatefrom data signals in the frame, and includes uplink physical channelinformation; allocating a second time slot within the frame that isdifferent to the first time slot for the base station to transmit acontrol signal in response to the beacon signal, the control signal forproviding a basis upon which the DE adjusts a transmission parameter;wherein allocating the second time slot to the control signal comprisesallocating the second time slot to the control signal using a first codeof a code domain and allowing another downlink signal that is not thecontrol signal to use a second code of the code domain to share thesecond time slot with the control signal, wherein the first code differsfrom the second code; and allocating other timeslots for the basestation to operate in full duplex frequency division duplex (FDD) mode.9. The controller of claim 8, wherein data signals are not allocated tothe first time slot.
 10. The controller of claim 8, wherein the firstand second time slots operate in full duplex FDD mode.
 11. Thecontroller of claim 8, wherein the transmission parameter comprisespower.
 12. The controller of claim 8, wherein the control signal isbased upon at least one factor from the group consisting of: path losscomputed based upon the received power of the beacon signal; time ofarrival of the beacon signal; and channel impulse response in responseto the beacon signal.
 13. The controller of claim 8, wherein the logicfor allocating a first time slot within a frame for the UE compriseslogic for allocating the first time slot within at least some successiveframes to different UEs for transmission of respective different beaconsignals, and the logic for allocating a second time slot within a framefor the base station comprises logic for allocating the second time slotto the base station for transmission of different control signals withinthe at least some successive frames to the different UEs.
 14. Thecontroller of claim 8, further comprising logic for determining to whichUE the first time slot should be allocated based upon at least onefactor from the group consisting of: expected volume of data transferexpected; required data transfer rate; frequency of short bursts of datatransfer; total number of UEs connected to the network; time since lastdata transfer; and UE power saving requirements.
 15. A computer-readablestorage medium comprising program code, executable by a processor, forenabling active control feedback between a base station and UE in awireless communications network, the program code for: allocating afirst time slot within a frame for a UE to transmit a beacon signal tothe base station, wherein the beacon signal is separate from datasignals in the frame, and includes uplink physical channel information;allocating a second time slot within the frame that is different to thefirst time slot for the base station to transmit a control signal inresponse to the beacon signal, the control signal for providing a basisupon which the UE adjusts a transmission parameter; wherein allocatingthe second time slot to the control signal comprises allocating thesecond time slot to the control signal using a first code of a codedomain and allowing another downlink signal that is not the controlsignal to use a second code of the code domain to share the second timeslot with the control signal, wherein the first code differs from thesecond code; and allocating other timeslots for the base station tooperate in full duplex frequency division duplex (FDD) mode.
 16. Thecomputer-readable storage medium of claim 15, wherein data signals arenot allocated to the first time slot.
 17. The computer-readable storagemedium of claim 15, wherein the first and second time slots operate infull duplex FDD mode.
 18. The computer-readable storage medium of claim15, wherein the transmission parameter comprises power.
 19. Thecomputer-readable storage medium of claim 15, wherein the control signalis based upon at least one factor from the group consisting of: pathloss computed based upon the received power of the beacon signal; timeof arrival of the beacon signal; and channel impulse response inresponse to the beacon signal.
 20. The computer-readable storage mediumof claim 15, wherein the program code for allocating a first time slotwithin a frame for the UE comprises program code for allocating thefirst time slot within at least some successive frames to different UEsfor transmission of respective different beacon signals, and the programcode for allocating a second time slot within a frame for the basestation comprises program code for allocating the second time slot tothe base station for transmission of different control signals withinthe at least some successive frames to the different UEs.
 21. Thecomputer-readable storage medium of claim 15, further comprising programcode for determining to which UE the first time slot should be allocatedbased upon at least one factor from the group consisting of: expectedvolume of data transfer expected; required data transfer rate; frequencyof short bursts of data transfer; total number of UEs connected to thenetwork; time since last data transfer; and UE power savingrequirements.